Information equipment, such as a car navigation device or a mobile phone, equipped with a character input device having an input prediction function is known. In a conventional character input device, when erroneously selecting a predicted candidate and then confirming the selection, the user needs to temporarily delete all of the selected character string which he or she has confirmed and input the same characters again. Thus, the efficiency of the character input is bad. Particularly, in a character input device, such as a car navigation device or a mobile phone, in which input keys are arranged in limited space, because a plurality of characters are assigned to each input key in many cases, and it takes much time for the user to input characters, an operation of re-inputting the same characters again requires a great deal of time.
To solve this problem, for example, patent reference 1 describes a character input device that enables the user to delete input character data displayed on the character input device and, even after making the character input device carry out kana-Chinese character conversion on an inputted character string and then confirming the conversion, enables the user to specify a phrase and then push down a clear key for commanding a return to the immediately-preceding operation or the like while kana characters in the next phrase are converted to Chinese characters to make the character input device return the confirmed character string to a kana character string yet-to-be-confirmed and carry out kana-Chinese character conversion on this character string again. Further, for example, patent reference 2 describes a character input device that in a mode of converting an inputted character string on a per phrase basis, enables the user to specify a phrase to be corrected to make the character input device carry out kana-Chinese character conversion on this phrase again even after carrying out kana-Chinese character conversion on the inputted character string when the user has not pushed down an enter key, but has pushed down a temporary enter key. In addition, for example, patent reference 3 describes a character input device that when the user erroneously selects a predicted candidate based on input characters and then confirms the selection, and, immediately after that, pushes down a delete key, deletes the predicted candidate which the user has selected erroneously and confirmed, and displays the characters inputted thereto before the confirmation.